I could see them introducing a 1 billion bounty at the very end when he has beaten everyone and has gotten One Piece. After this storyline I think it'll go up to about 250 million at least for taking down such a important marine base.

i guess that can happen for now. I hope his crew get some higher bountys. i mean zoro has a 60 million but robin has 79 million, zoro should get more. at least by the end of this arc. i heard sanji will get his bounty higher so i hope that happens

well seeing that he has to get through the marine base and defeat cp9 which are all marine so the bounty should go up my 100,000 to 150,000, because he also have to take back nico robin, and he is bond to come across some more of the pirate god people

I think his bounty will become very high. Because when he defeated Crocodile, his bounty increased from 30 Million to 100 Million. Well that was only 1 Person, but what happens if he beats all of the C9 agents and the other government guys, when he takes Robin with him and escapes from that prison.
After that i think his bounty will become like 500 Million or so...

By the way, does anyone know how high Whitebeards oder Shanks bounty is?

I don't think after this arc Luffy's bounty's gonna go higher than any one of the shichibukai, if he does it'll feel as if their rushing it. After this arc I think it's mainly gonna focus on new bountys like Sanji's and Sogeking's( yes Sogeking)

I don't think after this arc Luffy's bounty's gonna go higher than any one of the shichibukai, if he does it'll feel as if their rushing it. After this arc I think it's mainly gonna focus on new bountys like Sanji's and Sogeking's( yes Sogeking)

+1

and luffy had already a pretty big bounty... so i think they will put a buster call on them, and then who cares about bounty, cause they are dead
and bounties mostly serve for bounty hunters, so even if the price is enormous, i think they have surpassed the level of being threatened by hunters... (unless there exist a big organisation stronger than the government that we don't know about... DBZ power !!! :P )..